Impact Time from Image Sensing

1. A method to compute impact time between an image sensing circuitry and an object relatively moving at least partially towards, or away from, the image sensing circuitry, wherein the method comprises: receiving image data associated with a respective image frame of a sequence (1 . . . N) of image frames sensed by said image sensing circuitry and which image frames are imaging said object, identifying multiple pixel positions that are present within each of the image frames, computing, for each one (i) of the multiple pixel positions, a respective duration value (f(i)) indicative of a count of a number of consecutive frames during which the pixel position (i) is identified as being a local extreme point in said sequence (1 . . . N) of image frames, wherein the pixel position (i) is identified as being a local extreme point when an image data value of the pixel position (i) is identified as being either a maxima value or a minima value in relation to image data values of those pixel positions that are adjacent to said pixel position (i), and computing a slope value (k) by fitting a line to the duration values (f(i)) as a function of the multiple pixel positions, whereby the slope value (k) corresponds to the slope of the line.

2. The method as claimed in claim 1 , wherein the duration value is a largest number of consecutively occurring local extreme points in said sequence of image frames.

3. The method as claimed in any one of claims 1 - 2 , further comprising computing a sum (Σf(i)) of the duration values (f(i)).

4. A method to compute impact time between an image sensing circuitry and an object relatively moving at least partially towards, or away from, the image sensing circuitry, wherein the method comprises: receiving image data associated with a respective image frame of a sequence (1 . . . N) of image frames sensed by said image sensing circuitry and which image frames are imaging said object, identifying multiple pixel positions that are present within each of the image frames, computing, for each one (i) of the multiple pixel positions, a respective duration value (f(i)) indicative of a count of a number of consecutive frames during which the pixel position (i) is identified as being a local extreme point in said sequence (1 . . . N) of image frames, wherein the pixel position (i) is identified as being a local extreme point when an image data value of the pixel position (i) is identified as being either a maxima value or a minima value in relation to image data values of those pixel positions that are adjacent to said pixel position (i), and computing a slope value (k) based on an inverse (1/Σf(i)) of the sum multiplied with a predetermined constant scale factor (c), wherein said slope value (k) corresponds to: k = c ∑ ⁢ f ⁡ ( i ) , where c is said predetermined constant scale factor and Σf(i) is said sum of the duration values (f(i)).

5. The method as claimed in claim 4 , wherein the predetermined constant scale factor (c) corresponds to: c = ∑ ⁢ ⁢ 1  i  , where i is a respective pixel position of said multiple pixel positions.

6. The method as claimed in claim 4 , further comprising: computing an offset value (δ) indicative of an offset of a pixel position (i max ) of a maximum duration value amongst the computed largest duration values (f(i)) in relation to a centre image position (i centre ) of said multiple pixel positions, wherein the scale factor (c) corresponds to: c = ∑ ⁢ ⁢ 1  ( i - δ )  , where i is a respective image position of said multiple pixel positions and δ is said offset value.

7. The method as claimed in claim 1 , further comprising: computing the impact time using the computed slope value (k), wherein the impact time (T I ) corresponds to: T I = T ⁢ 1 + k k , where k is the computed slope value and T is the sample period of the image frames.

8. The method as claimed in claim 1 , wherein the multiple pixel positions corresponds to a subset of all pixel positions.

9. The method as claimed in claim 1 , wherein the multiple pixel positions are uniformly distributed amongst all pixels positions, or at least all pixel positions in an area of interest.

10. The method as claimed in claim 1 , wherein each one of said multiple pixel positions is associated with a respective pixel position.

11. A non-transitory computer readable medium having a program recorded thereon that, when executed by a computer, causes the computer to perform operations to compute impact time between an image sensing circuitry and an object relatively moving at least partially towards, or away from, the image sensing circuitry, wherein the operations comprise: receiving image data associated with a respective image frame of a sequence (1 . . . N) of image frames sensed by said image sensing circuitry and which image frames are imaging said object, identifying multiple pixel positions that are present within each of the image frames, computing, for each one (i) of the multiple pixel positions, a respective duration value (f(i)) indicative of a count of a number of consecutive frames during which the pixel position (i) is identified as being a local extreme point in said sequence (1 . . . N) of image frames, wherein the pixel position (i) is identified as being a local extreme point when an image data value of the pixel position (i) is identified as being either a maxima value or a minima value in relation to image data values of those pixel positions that are adjacent to said pixel position (i), and computing a slope value (k) by fitting a line to the duration values (f(i)) as a function of the multiple pixel positions, whereby the slope value (k) corresponds to the slope of the line.

12. A computer configured to perform operations to compute impact time between an image sensing circuitry and an object relatively moving at least partially towards, or away from, the image sensing circuitry, wherein the operations comprise: receiving image data associated with a respective image frame of a sequence (1 . . . N) of image frames sensed by said image sensing circuitry and which image frames are imaging said object, identifying multiple pixel positions that are present within each of the image frames, computing, for each one (i) of the multiple pixel positions, a respective duration value (f(i)) indicative of a count of a number of consecutive frames during which the pixel position (i) is identified as being a local extreme point in said sequence (1 . . . N) of image frames, wherein the pixel position (i) is identified as being a local extreme point when an image data value of the pixel position (i) is identified as being either a maxima value or a minima value in relation to image data values of those pixel positions that are adjacent to said pixel position (i), and computing a slope value (k) based on an inverse (1/Σf(i)) of the sum multiplied with a predetermined constant scale factor (c), wherein said slope value (k) corresponds to: k = c ∑ f ⁡ ( i ) , where c is said predetermined constant scale factor and Σf(i) is said sum of the duration values (f(i)).

13. An apparatus to compute impact time between an image sensing circuitry and an object relatively moving at least partially towards, or away from, the image sensing circuitry, wherein the apparatus comprises: a receiving port, configured to image data associated with a respective image frame of a sequence (1 . . . N) of image frames sensed by said image sensing circuitry and which image frames are imaging said object, and a first computing circuitry, configured to: identify multiple pixel positions that are present within each of the image frames, and compute, for each one (i) of the multiple pixel positions, a respective duration value (f(i)) indicative of a count of a number of consecutive frames during which the pixel position (i) is identified as being a local extreme point said sequence (1 . . . N) of image frames, wherein the pixel position (i) is identified as being a local extreme point when an image data value of the pixel position (i) is identified as being either a maxima value or a minima value in relation to image data values of those pixel positions that are adjacent to said pixel position (i); and a second computing circuitry, configured to compute a slope value (k) by fitting a line to the duration values (f(i)) as a function of the multiple pixel positions, whereby the slope value (k) corresponds to the slope of the line.

14. The apparatus as claimed in claim 13 , wherein the duration value is a largest number of consecutively occurring local extreme points in said sequence of image frames.

15. The apparatus as claimed in claim 13 , further comprising: a third computing circuitry, configured to compute a slope value (k) based on an inverse (1/Σf(i)) of the sum multiplied with a predetermined constant scale factor (c), wherein said slope value (k) corresponds to: k = c ∑ ⁢ ⁢ f ⁡ ( i ) , where c is said predetermined constant scale factor and Σf(i) is said sum of the duration values (f(i)).

16. The apparatus as claimed in claim 15 , wherein the predetermined constant scale factor (c) corresponds to: c = ∑ ⁢ ⁢ 1  i  , where i is a respective pixel position of said multiple pixel positions.

17. The apparatus as claimed in claim 15 , further comprising: a fourth computing circuitry configured to compute an offset value (δ) indicative of an offset of a pixel position (i max ) of a maximum duration value amongst the computed largest duration values (f(i)) in relation to a centre image position (i centre ) of said multiple pixel positions, wherein the predetermined constant scale factor (c) corresponds to: c = ∑ ⁢ ⁢ 1  ( i - δ )  , where i is a respective image position of said multiple pixel positions and δ is said offset value.

18. The apparatus as claimed in claim 15 , further comprising: a fifth computing circuitry, configured to compute the impact time using the computed slope value (k), wherein the impact time (T I ) corresponds to: T I = T ⁢ 1 + k k , where k is the computed slope value and T is the sample period of the image frames.

19. The apparatus as claimed in claim 15 , wherein the multiple pixel positions corresponds to a subset of all pixel positions.

20. The apparatus as claimed in claim 13 , wherein the multiple pixel positions are uniformly distributed amongst all pixels positions, or at least all pixel positions in an area of interest.

21. The apparatus as claimed in claim 13 , wherein each one of said multiple pixel positions is associated with a respective pixel position.

22. The apparatus as claimed in claim 13 , further comprising: the image sensing circuitry configured to sense the image frames of the sequence.

23. The apparatus as claimed in claim 22 , wherein: the image sensing circuitry comprises sensing elements, each one being associated with a pixel position and configured to capture light, wherein each sensing element is further configured to, in response to captured light, provide local image data corresponding to a pixel, and the first computing circuitry comprises computing elements, each computing element being associated with one of or a group of the sensing elements and thereby also corresponding pixel position/s, wherein a computing element that is associated with a pixel position/s that corresponds to one of the multiple pixel positions, is configured to compute the respective duration value (f(i)) based on local image data from the associated sensing element/s.